V.R415 — Blazar IGMF Bound

Blazar lower bounds (Fermi-LAT, MAGIC, H.E.S.S.): B_IGMF ≳ 10⁻¹⁵–10⁻¹⁶ G. τ-prediction 10–100 nG exceeds by many OOM. Key τ-prediction: IGMF concentrated in filaments, not uniform. Testable with SKA.